I have a Cattle Decapitation shirt that's a close-up picture of a slit human throat. I don't know if that would help or hurt traffic to my booth.

I don't think I'm going to bring any shirts with sleeves, that sounds like a thing to do in the summer in a parking lot.

I wear long sleeve shirts all the time at metal shows. I usually just raise the sleeve part up when the moshing and intense action starts to commence. Both summer and when ever at any venue, both in door or out door